Which pigment secreted by specialized cells in the skin is capable of absorbing ultraviolet light?
a) Keratin
b) Melanin
c) Melatonin
d) Carotene
e) Collagen
Answer: b
You might also like to view...
You have decided to ascend to the summit of Mount Everest where the partial pressure of oxygen in the atmosphere has been estimated to be about 54 mmHg. Once you breathe in this air, the partial pressure of oxygen in the alveoli drops even lower, due to displacement by the partial pressure of carbon dioxide and water vapor. The arterial concentration of oxygen at the pulmonary capillaries is measured and found to be 25 mmHg. What is the percent saturation of hemoglobin at this partial pressure?
A. 98% B. 83% C. 18 % D. 45%
Which of the following is not a difference between DNA and RNA?
What will be an ideal response?
Benzodiazepines act by increasing ________ activity.
A. enkephalin B. ACh C. glutamate D. GABA
The transfer of an electron from sodium to chlorine is an example of:
A) mechanical energy. B) sound energy. C) electrical energy. D) chemical energy.